Elastic fluid turbine diaphragm



June 10, 1941.

5. 0. TRUE X K ELASTIC FLUID TURBINE DIAPHRAGM Filed Dec. 13, 1939 IYwVerw tor: George O. Truex,

Hp s Autovrwey.

Patented June 10, 1941 ELASTIC FLUID TURBINE DIAPHRAGM George 0. Truex, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application December 13, 1939, Serial No. 309,006

3 Claims.

The present invention relates to elastic fluid turbine diaphragms having nozzles for conducting elastic fluid discharged from the bucket wheel of one stage to the bucket wheel of another stage. More specifically the invention relates to the type of diaphragms which include a nozzle structure in the form of a row or ring of spaced partitions or blades with inner andouter ends projecting into openings of inner and outer bands respectively and secured thereto by welding material.

The outer band of such structure is usually se-' curely fastened to a massive ring for supporting the diaphragm on a casing, while the inner band is secured to and acts as a support for a disk. To facilitate assembling and dismantling 01. atmbine, the diaphragms are made up of two halves suitably joined together and supported on the turbine casing. A diaphragm of this type is disclosed, for example, in the patent to H. A. Lacey No. 1,932,278, issued on October 24, 1933, and assigned to the same assignee as the present application.

In modern high pressure, high temperature turblnes it is important that the inner and outer bands of the nozzle or partition structure are securely fastened to or united with the outer ring and the disk respectively in order to attain the utmost rigidity necessary to withstand stresses set up due to high temperature changes and the impact of high velocity elastic fluid.

The object of my invention is to provide an improved construction and arrangement of elastic fluid turbine diaphragms whereby the nozzle structure may be securely united with such outer band and disk at comparatively low cost, and whereby accurate nozzle area and shape are maintained by reduced amount of welding.

For a consideration of what I believe to be novel and my invention, attention is directed to the following description and the claims appended thereto in connection with the accompanying drawing.

In the drawing Fig. 1 illustrates a section of a diaphragm, partly broken away, embodying my invention; Fig. 2 is a front view of Fig. 1; and Fig. 3 is a section along linel33 of Fig. 2.

The diaphragm comprises a nozzle structure having a plurality of circumferentially spaced partitions or blades 10 with inner ends secured to an inner band H and outer ends secured to an outer band I2. Each partition has walls curved in cross-section, as best shown in Fig. 3, with relatively thick inlet edges 13 and thin outlet edges 14. The thin outlet edges of the partitions or blades are subject to considerable bending forces during operation. In order to reduce the bending of the outlet edges by elastic fluid impinging thereon, I provide in accordance withmy invention each partition or blade with a reinforcing fin or web l5 integrally formed with the blade and uniting the thick inlet edges l3 with the thin outlet edges l4. These reinforcing fins extend axially from a point near the inlet edge i3 and about midway of the radial height of the partition to a point near the outlet edge H and eircumferentially from the inner surface of the partition to points near the outer surface of the adjacent partition, thus forming a small clearance between the outer surface of the partition and the reinforcing fin of an adjacent partition. A portion iii of the reinforcing fin of the partition is gradually reduced in thickness towards the outlet edge to permit substantially uniform discharge of elastic fluid from the nozzles formed by adjacent partitions. The fins of the partitions act as stifienings helping to resist creep, reduce stresses and to raise the nozzle frequency. In addition they act in directing elastic fluid to the bucket wheel and thereby to reduce impact onto the inner surface of the outer cover of the buckets of such wheel.

The nozzle structure, as pointed out before, has bands secured to an outer ring and a disk, all of these elements being made in two halves joined along a diameter of the disk. The outer ring in accordance with my invention is made up of two rings, an inner ring l1 and an outer ring l8. The inner ring and adiacent portions of the outer band I! form grooves IS on opposite sides which are fllled with welding material 20 whereby the ring I! which may comprise a plurality of segments is securely united with the band II. The

outer ring l8 has a groove 2| enclosing the inner and thereupon the outer ring is placed over the 7 inner ring l1 and in contact with the outer sur face of the outer band I! and united therewith by filling the aforementioned grooves 22 with the welding material 23. In some cases it may be desirable to heat the outer ring I8 prior to its assembly with the nozzle structure and the inner ring H in order thereby to procure a lateral shrinking flt between the inner and outer rings ll and I8.

The connection between the inner band H and the disk is similar, that is, the disk is made up of two parts, a disk proper 24 and a ring 25'disposed within a groove 26 of the disk proper 24. The ring 25 is fused to the inner band I l by welds 21 corresponding to the welds 20 with regard to the outer ring, and the disk proper 24 is fused to the inner band H by welds 28 filling grooves on opposite sides of the disk.

From another viewpoint, a diaphragm according to my invention comprises a nozzle structure with a plurality of circumferentially spaced partitions having ends projecting into and fused to inner and outer bands respectively. Each partition has relatively thin outlet edges which are stiffened by axially and circumferentially extending fins integrally formed on the midway portion of the partition. Inner and outer rings 25 and I1 respectively are welded to central portions of the inner and outer bands. Another outer ring with a circumferential groove in its inner surface encloses the first-mentioned outer ring and is welded to the outer band. A disk with a circumferential groove in its outer surface encloses said inner ring and is welded to the inner band.

The provision of an outer ring in the form of two parts separately welded to the outer band and similarly of a disk made up of two parts in the form of a disk proper and a ring separately welded or fused to the inner band results in great rigidity of the diaphragm and moreover may be produced at comparatively low cost. The low cost is mainly due to the relatively small amount of welding material needed for connecting the bands with the ring and the disk. A small amount of welding causes little distortion, which is one or the most difllcult troubles to overcome, with heavy welding. For example, the amount of welding material for filling the four grooves formed between the outer band and the outerring is considerably less than would be needed 'ends of the partitions,

it such outer ring were made solid, that is, of one part, and had to be secured to the band I: by large grooves formed between them as shown for example in the aforementioned patent. In case of integral, outer rings, such large grooves are necessary because it is essential that they extend substantially near the central portion of the band. The same is true with regard to the saving in welding material accomplished by making the disk in two parts as described above.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. Elastic fluid turbine diaphragm comprising a nozzle structure with a plurality of partitions and an inner and an outer band connecting the ends of the partitions, a disk secured to the inner band, a ring welded to a central portion of the outer band and another ring with a groove engaging opposite sides of the first-mentioned ring and welded to outer portions of the outer band.

2. Elastic fluid turbine diaphragm comprising a nozzle structure with a plurality of partitions and an inner and an outer band connecting the ends of the partitions, an outer ring welded to the outer band, an inner ring welded to a central portion of the inner band, and a disk with a circumferential groove in its outer surface accommodating the inner ring and welded to outer portions of the inner band.

3. Elastic fluid turbine diaphragm comprising a nozzle structure with a plurality of partitions and an inner and an outer band connecting the rings on central portions of the inner and outer bands, an outer ring having a groove accommodating the ring on the outer band and being united with edge portions of the outer band, and a disk having a groove accommodating the ring on the inner band and being united with edge portions of the inner band.

GEORGE O. 'I'RUEX. 

